Electronic, page-based documents displayed on the Internet may contain both text and images, e.g., catalogs, brochures, magazines, books, financial reports, and the like. Prior systems and methods for displaying these documents require providing these documents in their native file format, e.g., MICROSOFT WORD®, QUARK®, PAGEMAKER®, and the like require the user to install and run specific application programs in order to view these documents. Alternatively, these documents may be converted to one or more page description files, such as postscript, or the ADOBE® PDF file format, which requires a PDF viewing program or plug-in, such as the ADOBE® Reader to be installed on the user's computer before the PDF file can be viewed. After the plug-in is installed, the desired PDF document is downloaded and viewed via any standard Web browser, such as the INTERNET EXPLORER® or NETSCAPE® programs.
One prior technique to overcome the need for users to install a PDF application program or plug-in is to convert the PDF file with images therein to an image file in a format such as JPEG (Joint Photographic Experts Group), PNG (Portable Network Graphics) or GIF (Graphic Interchange Format) which are typically supported by all standard Web browsers. PNG files can be optimized to provide a compact, high-quality representation of vector line drawings (e.g., text) in the page description file. However, incorporation of images from the page description file significantly increases the size of the PNG file, which leads to increased download time and storage requirements. GIF files are limiting because they can only support images with a maximum of 256 colors. The JPEG format allows a relatively compact file with high image quality representation of the images in the page description file to be produced by using a lossy compression method, but this results in poor quality vector line drawings and text. The JPEG format allows both high-quality line drawings (text) and images when lossy compression is not utilized, but files produced in this way are very large.